Dakota Dino Reveals Skin Cells
“Absolutely amazing” and “absolutely gobsmacking” are exclamations made by scientists analyzing the fossilized skin of a hadrosaur known as Dakota. The researchers found cell structures and organic matter in the skin and layers that resemble the skin of birds and crocodiles.
The specimen was uncovered in 1999 on a North Dakota ranch and is still being analyzed. Photos on the BBC News show clear scales and cross sections of microscopic tendon structures. The article said, “Tests have shown that the fossil still holds cell-like structures,” adding, “although the proteins that made up the hadrosaur’s skin had degraded, the amino acid building blocks that once made up the proteins were still present.”
How could soft tissue structures and details survive intact for 66 million years? The BBC article and National Geographic News repeat the researchers’ claim that this dinosaur was buried rapidly in a low-oxygen environment that prevented decay. Even so, it was unexpected to find this much preservation over such a long time. Derek Briggs, a Yale paleontologist who studies exceptionally-preserved fossils, said, “This kind of discovery just demonstrates very clearly that soft tissue does survive, that the processes involved are unusual but not absolutely extraordinary – so there’s no reason why this kind of material won’t be discovered again.”
Edmontosaurs annectens. Credit: Nobu Tamura, Wiki Commons.
Briggs told the BBC News that one reason paleontologists have not found soft tissues before recently is that they were not expecting to find them: “in many cases these kinds of skin impressions have gone unnoticed and people have gone after the skeleton, which is of course what you’d expect to be preserved.” Phillip Manning, author of a new book Grave Secrets of Dinosaurs: Soft Tissues and Hard Science expects a lot more soft tissue could be out there awaiting discovery: “Who knows?” he said. “The elusive dinosaur mummies of the fossil record might be more common.”
The National Geographic article, true to form, emphasized the similarity of Dakota’s skin to that of birds (cf. 06/18/2009). “There’s no evidence of goosebumps just yet,” quipped reporter Christine Dell’Amore, “but a remarkably preserved dinosaur reveals that the prehistoric reptile had skin like that of birds and crocodiles, a new study says.”
Why are the scientists so sure that an oxygen-free environment would preserve amino acids and mummified skin from degradation for 66 million years? This should be a testable hypothesis. There are anoxic bacteria, after all. Could they not be capable of degrading organic matter? And Dakota was not found in an underwater oxygen-free tomb, but in rock. Someone should put two identical dead animals in two tanks, one with oxygen and one without, simulating plausible burial environments, and measure the differences in decay rates. Besides, whatever organic material was left after the environment changed to rock should have decayed completely. Unless, that is, the fossil is nowhere near as old as the consensus believes.